<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"
          name="viewport">
    <meta content="ie=edge" http-equiv="X-UA-Compatible">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        /* 让容器的宽度和高度都充满全屏 */
        html, body {
            width: 100%;
            height: 100%;
        }

        body {
            background-color: pink;
            display: flex;
            flex-direction: row;
            align-items: center;
            justify-content: center;
        }

        .heart {
            width: 200px;
            height: 200px;
            background-color: red;
            position: relative;
            transform: rotate(45deg);
            animation: heartbit 1s alternate infinite;
            box-shadow: 0 0 30px red;
        }

        .heart::before {
            content: "";
            width: 200px;
            height: 100px;
            background-color: red;
            position: absolute;
            left: 0;
            top: -99px;
            border-radius: 100px 100px 0 0;
            box-shadow: 0 0 30px red;
        }

        .heart::after {
            content: "";
            width: 100px;
            height: 200px;
            background-color: red;
            position: absolute;
            left: -99px;
            top: 0;
            border-radius: 100px 0 0 100px;
            box-shadow: 0 0 30px red;
        }

        /* 实现动画，让心跳动起来 */
        @keyframes heartbit {
            0% {
                transform: rotate(45deg) scale(0.6);
            }
            /*25% {*/
            /*    transform: rotate(45deg) scale(0.8);*/
            /*}*/
            /*50% {*/
            /*    transform: rotate(45deg) scale(1);*/
            /*}*/
            /*75% {*/
            /*    transform: rotate(45deg) scale(1.2);*/
            /*}*/
            100% {
                transform: rotate(45deg) scale(1.4);
            }
        }
    </style>
</head>
<body>

<div class="heart"></div>

</body>
</html>